Paralleling

In simple terms "paralleling" means to feed a common electrical bus with multiple generators to provide more power to the electrical system than a single generator can produce. The power provided is the sum of the kilowatt (kW) rating of the generator sets. For instance, we can use three 500kW generators running in parallel to provide a 1500kW capability to feed the load.

Paralleling generators has always been considered complicated, expensive, and, therefore, reserved for only very large generator systems.  It has been rare to see generators rated less than 1000kW in paralleling systems, and most often paralleling was only used in systems requiring 3000kW or above.  Until a few years ago, the largest single internal combustion engine (ICE) driven generator set was 2000kW.  This meant a 3000kW need would have been met with three 1000kW or two 1500kW generators and use conventional paralleling switchgear.  Today we see ICE units used in standby power applications effectively up to 2500kW, but these units are rather costly in terms of initial purchase and maintenance.

Paralleling two generators is technically quite simple.  All it takes is for the generators to be operating at the same voltage, frequency and be rotating in the same direction - called having the same phase rotation. A competent technician with two meters can parallel two generators.  The complicated part of the system has always been the switchgear required for controlling the paralleling operation, and the expense of this equipment.

As it is with every industry, computer technology allows us to put the electronics that used to require a cabinet size of a typical refrigerator, in a box the size of a lap top computer.  How fitting - pun intended!  The Generac Modular Power System (MPS), with the paralleling built in to each generator, alleviates the road blocks to paralleling of the past, and makes it a truly cost effective option for consideration in any application desiring the inherent benefits a paralleling system offers.  Key benefits are:

• Redundancy - If a single unit is down, the entire plant is down.  Multiple units provide capability for maintaining partial functionality if one unit is down for any reason.
• Scalability - Plants are often installed with more on-site power generation than is needed today because of future growth needs.  The modular concept allows the owner to install what is needed now, for less cost, and very easily add units as needed.
• Reliability - Multiple smaller units are easier to maintain than a single large unit, and allow for service being performed without disrupting the entire back up power system.
• N+1 Capability - adding one additional smaller unit over what is required to carry the load provides a cost effective approach to achieving "5-9's" reliability.
• Installation - Multiple units are easier to install than a single large unit.  Setting the units requires smaller cranes and connections are easier for the electrician to install.
• Serviceability - Smaller multiple units are much more easily serviced than the single large units, and parts costs are less because the engines are produced in large volumes resulting in lower equipment costs.
• Availability - lead times for the Modular Power System are significantly less than the single large units.
• Capital Cost - The initial capital cost for multiple units is often less than a single unit.

With thousands of installations now using this advanced paralleling technology nationwide, modular power systems are proven, reliable, and cost effective solutions for the most critical applications.  Where redundancy in the generator system was not a viable [cost effective] option in the past, our systems open this option to all applications.  Let us know how we can help with design and specifying a system for you. 
 
Don Leher
Industrial Sales Manager
GEN-TECH